Indicator



y ,1931. A. MEISSNER ET AL 1,814,399

INDICATOR Filed Aug. 19. 1927 INVENTOR ALEXANDER MEISSNER BY 5}) VON BRONK /l a Pdbwoo TORNEY Patented July: 14, 1931 I UNITED s'mras GESELLSCHAFT FUR DRAHTLOSE TELEGRAPHIE M. B. H. HALLESCHES, OF BERLIN,

PATENT OFFICE ALEXANDER MEISSNER AND OTTO VON BRONK, BERLIN, GERMANY, ASSIGNOBS TO GERMANY, A CORPORATION OF GERMANY INDICATOR 'Application filed August 19, 1927, Serial No. 214,098, and in .Germany August 21, 1926.

This invention relates to a device for indicating alternating potentials.

Arrangements for the indication of alternating potentials, especially high frequency 5 oscillations are known in which a quartz crystal is confined within anexhausted vessel filled with gas so that the potentials set up at the quartz body cause the tube to luminesce. This device involves the great drawback that, on the one hand, it gives rise to very small luminous energy, inasmch as the'potentials across the quartz crystal in the low vacuum are very small. On the other hand, difliculties arise insofar as it is necessary to reinove the crystal from the vacuous space and to remount and reseal ittherein after grinding away portions thereof whenever it is a desired to change the wave of the-crystal, in other words, whenever the indicator is to be adapted so as to respond to another, wavelength. The present invention avoids these drawbacks and thus discloses essential technical progress. This progress is attained in that the crystal influenced by the alternating current to be observed, as soon as it happens i to be in resonance with the frequency to be influenced, is electrically connected with a luminous orglow-discharge tube located outside the crystal in such a way that the energy of the oscillating crystal fexcites said luminous tube at the instant when resonance arises. This excitation may be further in-. tensified by applyingan auxiliary (biasing) 5 potential across the terminals of-the luminous tube wherebythe breakdown (striking) potential of the tube, is lowered.

Embodiments ofthe basic idea of our invention are shown by way of example in then 0 accompanying drawmgs wherein Fig. 1 shows one form of our invention and I Fig. 2 shows'a modified form of our'invention utilizing an exciting battery for a glow discharge tube. In Fig. 1 Q is a piezo-electric body, say, a quartz crystal, and L a coil which serves for establishing a coupling with the transmitter to be checked. In series with the crystal is arranged a glow-discharge or a helium tube 9 G." By the excitation by the transmitter, the 1 quartz crystal will be caused to oscillate,-

energy being given off by the crystal at the instant it starts to oscillate, to the luminous system coupled therewith, the latter being caused to flash up at the instant the quartz crystal happens to be in resonance.

In Fig. 2 we have shown an embodiment of our-invention wherein the glow tube G is kept in a critical condition by means of battery H.

Of course, care must rangement so that the flashing up of the luminous tube will not be caused by the direct energy of the oscillation to be controlled, but only bythe energy of the quartz crystal itself The coupling between the be taken in this arquartz crystal and the luminous tube may be inductive, capacitive oi galvanic.

We claim as our invention: g 1. In combination, a glow discharge .device, a source of potential forkeeping said device in a critical condition, a piezo electric crystal and an inductor in series with said glow discharge device, and means for supplying an alternatingpotential to said inductor.

'2'. In combination, a piezo electric crystal, a glow discharge device and an impedance in series; a source of potential shunted across said gloiw discharge device and means for supplying an alternating potential to said impedance whereby-when said potential corresponds in frequency to that of the crystal,

.a discharge occurs across said glow discharge device. J

' ALEXANDER MEISSNER.

OTTO VON BRONK. 

